Photographic colour diffusion transfer process and photographic recording material suitable therefor.

0001The invention relates to a process for producing color photographic images by the dye diffusion transfer process and to a photographic material suitable for this purpose which contains new diffusion-resistant, oxidizable coloring compounds which release diffusing dyes in non-oxidized form.

0002Among the processes known to date for producing colored photographic images using the color diffusion transfer process, those based on the use of diffusion-resistant embedded coloring compounds, from which diffusing dyes or dye precursor products are separated imagewise during development and transferred to an image-receiving layer, have recently become increasingly important . The color-providing compounds suitable for this purpose include, for example, the non-diffusing color couplers described in DE-PS 1 095 115, which, during development as a result of a reaction with the oxidation product of a color developer compound consisting of a primary aromatic amine, form a pre-formed dye or a dye produced during color coupling set free in diffusing form. The selection of the developer compound required is naturally limited to color developers.

0003Furthermore, reference should be made to the non-diffusing coloring compounds described in DE-OS 1 930 215, which contain a preformed latent diffusible dye residue linked to a diffusion-proofing residue via a cleavable hydrazone group. These compounds are not to be referred to as color couplers, and it has also been found that the selection of developer compounds which are required to release the diffusing dye residue is in no way limited to the customary color developers, but also that black and white developers, for example pyrocatechols, are also used , are very useful.

0004DE-OS 1 772 929 also describes non-diffusing colored compounds with a special grouping which undergo an oxidative ring closure reaction during development and thereby release a pre-formed dye residue in diffusing form. The connections presented there can be divided into two groups. The compounds of the one group require a customary color developer compound for development, with whose oxidation product they couple and in a subsequent ring closure reaction release the pre-formed dye residue in diffusing form. The compounds of the other group are themselves slip halide developing agents and are therefore able, in the absence of further developer compounds in the oxidustan form, to undergo the above-mentioned ring closure reaction with fralse tion of the diffusing dyes.

0005Finally, the non-diffusing coloring compounds of DE-OS 2 242 762 should also be mentioned at this point. These are sulfonamidophenols and sulfonamidoanilines, which after development have undergone oxidation under the influence of the developer alkali with the release of diffusing dyes with a free sulfamoyl group become.

0006The above-mentioned coloring compounds work invariably negative, ie the imagewise distribution of the diffusing dye set arises when conventional (negative working) silver halide emulsions are used in accordance with the negative silver image produced during development. To produce positive finished fabric images, it is therefore necessary to use direct-positive silver halide emulsions or, otherwise, to use a suitable reversal process.

0007Non-diffusing coloring compounds are also known from German Offenlegungsschriften 2 402 900 and 2 543 902, which, in non-oxidized form, are capable of a cleavage reaction under alkaline development conditions, a diffusing color step being set free, and in which, on the other hand, in the oxidized form the one mentioned above Cleavage reaction is difficult or prevented. Such compounds are suitable in combination with conventional negative emulsions for producing positive transfer color images

0008Another class of non-diffusing oxidizable compounds, which predominantly release only from the non-oxidized form of diffusing dyes, is the subject of German patent application P 28 23 159.6. The compounds described there are essentially those of the following formula:<chemistry id="chem0001" num="0001"><img file="EP0012908A2_D0001.tif" /></chemistry>in which mean:<ul id="ul0001" list-style="none"><li>A is a photographically effective group which, together with the link -Z- (X)_mis split off from the non-oxidized form of the oxidizable compound under alkaline conditions;</li><li>Y¹ and Y² (identical or different) groups which, owing to their interaction with one another, can be oxidized to form a p-quinoid system;</li><li>R¹ an optionally substituted hydrocarbon residue;</li><li>R² Hydrogen or an optionally substituted hydrocarbon radical;</li><li>R3 R⁴ and R⁵ (same or different) hydrogen, halogen, alkyl or alkoxy with up to 18 carbon atoms, _Acy_la_mi_no or _R³ together with R⁴ the rest necessary to complete a condensed, optionally substituted hydrocarbon ring</li></ul>and wherein at least one of the substituents R¹, R³, R⁴ and R⁵ contains a diffusion-proofing residue.

0009With the compounds described in the aforementioned German patent application P 28 23 159.6, positive colored transfer images can be generated using conventional negative-working silver halide emulsions, but these still have a certain color haze, which indicates that the combinations used in the oxidized state are not sufficiently stable are to be protected against subsequent splitting under the alkaline, development conditions. However, color-imparting compounds of the type described which are completely stable in the oxidized form under the development conditions are desired.

0010Upon further processing of this technical field, it has now been found that results are obtained which are substantially more favorable, ie compounds whose oxidized form is more stable against alkaline cleavage if those compounds are selected from the substance class described in the aforementioned German patent application in which neither in the (free) o- nor in the p-position to the cleavable residue -S0₂- (X)_m-A bearing carbon atom is a deprotonatable group such as -OH or -NH₂ is present or can arise in an alkaline developer environment. It should be noted that one of the two o-positions to the said carbon atom is necessary.

0011must be substituted with such a group which, together with a second group of the same type, enables the formation of a p-quinoid system upon oxidation. It is important that positions 2 and 4 of the above formula contain neither a hydrogen atom nor a substituent that can be exchanged for OH ions.

0012The invention relates to a photographic diffusion transfer process, in which a photographic material with at least one light-sensitive silver halide emulsion layer and an associated non-diffusing oxidizable compound which, in non-oxidized form, is subject to a cleavage reaction under the conditions of alkaline development with the release of a photographically active group, for example of a diffusing dye, and which is not or only to a much lesser extent subject to the mentioned cleavage reaction in the oxidized form than in the non-oxidized form, is imagewise exposed and developed with a silver halide developing agent, the silver halide developing agent oxidizing the non-diffusing oxidizable compound in oxidized form and thereby converting it into a Alkali not converted or only slightly fissile form, while the photographically active group is released from the imagewise distribution of non-oxidized oxidizable compound as a result of cleavage by alkali. If the photographically active group is a diffusing dye, this can be transferred to an image-receiving layer. In the latter case, the non-diffusing compounds are referred to below as coloring compounds. The process is characterized in that a compound of the following formula is used as the non-diffusing oxidizable compound:<chemistry id="chem0002" num="0002"><img file="EP0012908A2_D0002.tif" /></chemistry>in which mean:<ul id="ul0002" list-style="none"><li>A the rest of a photographically active group, especially the rest of a diffusing dye or dye precursor;</li><li>X is a bivalent link of the formula -R- (L)_p- (R)_q-, in which R is an alkyl radical having 1-6 C atoms or an optionally substituted arylene or aralkylene radical and where the two radicals R may have the same or a different meaning;</li><li>L -0-, -CO-, -CONR⁶-, -SO₂NO⁶-, -O-CO-NO⁶-, -_S-, -SO- or -S0₂- (R = hydrogen or alkyl),</li><li>p 0 or 1;</li><li>q 0 or 1;</li><li>m 0 or 1; Y¹ and Y² (identical or different) groups or precursors of groups which can be oxidized due to their interaction with one another to form a p-quinoid system, for example -OR⁷--NHR⁷, -NH-R⁸, -NO⁸)₂ or -NH-SO₂-R⁸, where R⁷ represents hydrogen or a photographically inert group which can be hydrolyzed under the alkaline development conditions and R⁸ stands for any organic photographically inert radical which is linked via a carbon atom with the nitrogen atom or the -S0₂Group is connected, preferably for alkyl, in particular lower alkyl having 1 to 4 carbon atoms, or aryl, in particular phenyl or tolyl; Y² however, is not a disubstituted. Amino group -N (R⁸)₂;</li><li>R is an optionally substituted hydrocarbon radical, for example alkyl with up to 2₂ Carbon atoms, such as methyl, ethyl, n-hexyl, n-octyl, n-undecyl, n-dodecyl, n-tridecyl, n-heptadecyl, aralkyl such as benzyl or aryl such as phenyl;</li><li>R² Hydrogen or an optionally substituted hydrocarbon radical, for example alkyl having up to 22C atoms, such as methyl, ethyl, propyl, isopropyl, n-hexyl, n-octyl, n-undecyl, n-dodecyl, n-tridecyl, n-heptadecyl, aralkyl such as benzyl, or aryl such as phenyl;</li><li>R³ a substituent as for R² defines a grouping that together with R⁴ completes a condensed heterocyclic or carbocyclic, optionally aromatic ring or OH, halogen such as chlorine or bromine, amino, alkylamino, dialkylamino including cyclic amino groups (such as piperidino, morpholino), acylamino, alkylthio, alkoxy, aroxy or sulfo;</li><li>R⁴ an optionally substituted hydrocarbon. residual material, for example alkyl with up to 22 carbon atoms, aralkyl such as benzyl, aryl such as phenyl or a group which together with R³ completes a fused-on heterocyclic or carbocyclic, optionally aromatic ring, for example a fused-on benzene or 2-bicyclo [2,2,1] heptene ring;</li><li>R⁵ an optionally substituted hydrocarbon. residual material, for example alkyl, aralkyl or aryl, preferably n-propyl,</li></ul>and wherein at least one of the substituents R¹, R³, R and R⁵ contains a diffusion-proofing residue.

0013The present invention furthermore relates to a material for carrying out the above method, which accordingly, in association with at least one light-sensitive silver halide emulsion layer, contains a non-diffusing oxidizable compound of the type described above.

0014In principle, the residues of dyes of all classes of dyes are suitable as dye residues insofar as they are sufficiently diffusible to diffuse through the layers of the light-sensitive material into the image-receiving layer. For this purpose, the dye residues can be provided with one or more water-solubilizing groups. Suitable water-solubilizing groups include carboxyl groups, sulfo groups, sulfonamide groups and aliphatic or aromatic hydroxyl groups. The sulfinic acid group remaining in the dye after the cleavage can already give the dye molecule a considerable tendency to diffuse in the alkaline medium, so that the presence of additional water-solubilizing groups is not absolutely necessary. Examples of dyes which are particularly suitable for the process according to the invention include azo dyes, azomethine dyes, anthraquinone dyes, phthalocyanine dyes, indigoid dyes, triphenylmethane dyes and metal complex dyes or colored metal complexes.

0015The residues of dye precursors are to be understood as the residues of those compounds which, in the course of photographic processing, are subjected to customary or additional processing steps, either by oxidation, by coupling or by exposure of an auxochromic group in a chromophoric system, for example by saponification Dyes are transferred. Dye precursors in this sense can be leuco dyes, couplers or dyes that are converted into other dyes during processing. Unless a distinction is made between dye residues and the residues of dye precursors, the latter should also be understood below as dye residues.

0016The bivalent link X shown in the general formula can, for example, be a radical of one of the following formulas:<chemistry id="chem0003" num="0003"><img file="EP0012908A2_D0003.tif" /></chemistry><chemistry id="chem0004" num="0004"><img file="EP0012908A2_D0004.tif" /></chemistry><chemistry id="chem0005" num="0005"><img file="EP0012908A2_D0005.tif" /></chemistry> Y¹ and Y² are preferably hydroxyl. Fllas Y¹ and / or Y² is an -NH-S02R8 group, R has⁸ The meaning of a photographically inert radical, for example an unsubstituted alkyl or phenyl radical, is advisable.

0017It goes without saying that, within the group of the oxidizable compounds of the general formula, some are more suitable than others. For example, by varying the substituent R³ the redox potential of the oxidizable compound is easily influenced and in this way adapted to practical requirements. It has already been pointed out that according to the invention, when selecting the substituents R⁴ and R⁵ is subject to certain restrictions insofar as this is hydrogen or others through OH^--Ions exchangeable substituents are out of the question. However, this does not apply to R to the same extent³ to, so that a larger selection of substituents is available here for setting the desired redox potential. In addition to being oxidizable, another important function of the compounds according to the invention is the easy hydrolyzability in the unoxidized form. The hydrolytic cleavage should proceed as quickly as possible in the alkaline developer medium so that the photographically active group is quickly released. On the other hand, the onset of hydrolytic cleavage should be delayed until the imagewise oxidation of the oxidizable compounds by developer oxidation products has essentially been completed. The rate of hydrolytic cleavage must therefore be adapted to the rate of oxidation and this can easily be achieved by varying the substituents which have a great influence on the hydrolyzability. This is among other things influenced by the nature of the link (x)_m, but primarily by the nature of the substituents, R, R and Y² within the given definition. If y₂= OH, for example R is preferably hydrogen. It should be noted that the coloring compounds according to the invention should not diffuse as intact molecules in the layers of the photographic material. For this purpose, they contain a diffusion-resistant radical, for example in one of the substituents R to R or in a substituent present on the fused ring completed by R together with R 4.

0018Adequate diffusion resistance of the coloring compounds can already be provided even if the substituents mentioned do not contain any longer alkyl residues, since the molecule can also have a sufficient size, depending on the dye residue. Otherwise it is possible to make the coloring compounds sufficiently diffusion-resistant by selecting residues of a suitable size.

0019Residues which make it resistant to diffusion are those which make it possible to store the compounds according to the invention in a diffusion-resistant manner in the hydrophilic colloids usually used in photographic materials. Organic radicals which generally contain straight-chain or branched aliphatic groups and optionally also isocyclic or heterocyclic or aromatic groups with generally 8-22 C atoms are preferably suitable for this purpose. These residues are either directly or indirectly connected to the rest of the molecule, for example via one of the following groups: -NHCO-, NHSO₂, -NR-, where R is hydrogen or alkyl, -O-, -S- or -SO₂ such hetero atom-containing groups expediently by at least two carbon atoms or methylene groups from the aromatic ring of the general formula (R³, R⁴, R⁵) or from which the cleavable group -SO₂- (X)_m-A) bearing carbon atom (R¹) are separated. In addition, the diffusion-proofing radical can also contain water-solubilizing groups, such as sulfo groups or carboxyl groups, which can also be in anionic form. Since the diffusion properties depend on the molecular size of the total compound used, it is sufficient in certain cases, for example if the total molecule used is large enough, to use shorter-chain residues as "diffusion-resistant residues".

0020Examples of non-diffusing oxidizable compounds suitable according to the invention are listed below:<chemistry id="chem0006" num="0006"><img file="EP0012908A2_D0006.tif" /></chemistry><chemistry id="chem0007" num="0007"><img file="EP0012908A2_D0007.tif" /></chemistry><chemistry id="chem0008" num="0008"><img file="EP0012908A2_D0008.tif" /></chemistry><chemistry id="chem0009" num="0009"><img file="EP0012908A2_D0009.tif" /></chemistry><chemistry id="chem0010" num="0010"><img file="EP0012908A2_D0010.tif" /></chemistry><chemistry id="chem0011" num="0011"><img file="EP0012908A2_D0011.tif" /></chemistry><chemistry id="chem0012" num="0012"><img file="EP0012908A2_D0012.tif" /></chemistry><chemistry id="chem0013" num="0013"><img file="EP0012908A2_D0013.tif" /></chemistry><chemistry id="chem0014" num="0014"><img file="EP0012908A2_D0014.tif" /></chemistry><chemistry id="chem0015" num="0015"><img file="EP0012908A2_D0015.tif" /></chemistry><chemistry id="chem0016" num="0016"><img file="EP0012908A2_D0016.tif" /></chemistry><chemistry id="chem0017" num="0017"><img file="EP0012908A2_D0017.tif" /></chemistry><chemistry id="chem0018" num="0018"><img file="EP0012908A2_D0018.tif" /></chemistry><chemistry id="chem0019" num="0019"><img file="EP0012908A2_D0019.tif" /></chemistry><chemistry id="chem0020" num="0020"><img file="EP0012908A2_D0020.tif" /></chemistry><chemistry id="chem0021" num="0021"><img file="EP0012908A2_D0021.tif" /></chemistry><chemistry id="chem0022" num="0022"><img file="EP0012908A2_D0022.tif" /></chemistry><chemistry id="chem0023" num="0023"><img file="EP0012908A2_D0023.tif" /></chemistry><chemistry id="chem0024" num="0024"><img file="EP0012908A2_D0024.tif" /></chemistry><chemistry id="chem0025" num="0025"><img file="EP0012908A2_D0025.tif" /></chemistry><chemistry id="chem0026" num="0026"><img file="EP0012908A2_D0026.tif" /></chemistry><chemistry id="chem0027" num="0027"><img file="EP0012908A2_D0027.tif" /></chemistry>

Production Example I

Compound No. 1

Step 1: 2,3-dimethyl-6-tetradecanoyl hydroquinone

0021Boron trifluoride was introduced into a mixture of 138 g (1 mol) of 2,3-dimethylhydroquinone 370 g (1.62 mol) of myristic acid and 700 ml of methylene chloride under vigorous reflux (bath temperature 50 ° C.) until saturation. After standing overnight, the reaction mixture was decomposed by stirring in 3 liters of 10% Na acetate solution. The methylene chloride was removed with steam. After cooling, the remaining oily layer solidified to a melt cake which was isolated by decanting. The melt cake was then melted and stirred into 2 liters of high-boiling gasoline. The precipitate was filtered off and washed with gasoline (50 - 70 ° C). After drying, the mixture was stirred with acetonitrile and suction filtered.

Yield: 260 g / F 100-101 ° C

Step 2: 4-hydroxy-2,3-dimethyl-6-tetradecanoylphenyl allyl ether

002263 g of potassium carbonate and 1200 ml of methyl ethyl ketone were added dropwise to 43 g of allyl bromide with gentle boiling over a period of 2 hours to a mixture of 105 g of ketone from stage 1. After 9 hours of boiling, the mixture was cooled to 30 ° C. and 200 ml of water were added.

0023The aqueous layer was separated. The organic light was shaken out once with 25% sodium chloride solution, separated off and the solvent was distilled off. The residue was stirred with 1 l of methanol and suction filtered.

0024Yield: 95 g / F 65-66⁰C.

Step 3: 2,3-dimethyl-5-allyl-6-tetradecanoyl hydroquinone

002590 g of allyl ether from stage 2 were heated to 210 ° C. in the course of 2 hours under a nitrogen atmosphere. After cooling, the melt was dissolved in 300 ml of gasoline (50-75 ° C) and cooled. The next day, the resulting precipitate was suctioned off.

Yield: 73 g / F 68-69

0

C.

Step 4: 2,3-dimethyl-5-propyl-6-tetradecanoyl hydroquinone

002616.2 g of the allyl compound from stage 3 were dissolved in 165 ml of alcohol and hydrogenated in the presence of Raney nickel under normal conditions. After removal of the Raney nickel, the alcohol was distilled off and the residue was crystallized from 300 ml of gasoline.

0027Yield: 15 g / F 69-70 ° C

Step 5: 2,3-dimethyl-5-propyl-6-α-hy3roxytetradecylhydroquinone

0028₁4th g of the keto compound from stage 4 were dissolved in 390 ml of methanol and a solution of 1.97 g of sodium borohydride in 24 ml of water was slowly added while stirring in a nitrogen atmosphere. After 30 minutes, the mixture was made weakly acidic with glacial acetic acid and stirred in a solution of 2.5 ml of sulfuric acid in 270 ml of water. The precipitate was filtered off and recrystallized from methanol.

0029Yield: 10.5 g / F 140-142 ° C

Step 6: dye sulfinic acid 4- (4-hydroxy-3-N, N-diethylsulfamoyl-8-methylsulfonamido-1-naphthylazo) -benzenesulfinic acid

0030Under a nitrogen atmosphere, 11.5 g of Na salt of 4-amino-benzenesulfinic acid and 4.4 g of sodium nitrite were added. 70 ml of water dissolved, mixed with 85 g of crushed ice and mixed with 18 ml of concentrated hydrochloric acid with stirring. The diazonium salt solution was immediately stirred in one solution into a solution of 25 g of 1-hydroxy-2-N, N-diethylsulfamoyl-5-methylsulfonamido-naphthalene, 23.15 g of sodium carbonate, 130 ml of water and 45 ml of acetone. After 30 minutes, the dye solution was stirred into 200 ml of glacial acetic acid and the dye which had precipitated was filtered off with suction. After drying in a vacuum desiccator, 32 g of crude dye remain, which was used without purification for the reaction to compound 1.

Level 7: Connection 1

0031To a solution of 4 g of the carbinol compound from stage 5 in 300 ml of glacial acetic acid heated to 60 ° C. was added a solution of 7 g of dye sulfinic acid from stage 6, 1.5 g of anhydrous Na acetate, 120 ml of glacial acetic acid and 40 ml of water. The mixture was heated to 90 ° C. for 2 hours while stirring in a nitrogen atmosphere. After a short time, the dye compound begins to fail. After cooling to 60 ° C, the resulting precipitate was filtered off and washed with glacial acetic acid. The dye was purified by stirring with methanol.

Yield: 5.6 g

Production Example II

0032Compound No. 11

Step 1: 2-methyl-5-hexadecanoyl hydroquinone

003313.7 g of 2-methylhydroquinone and 45 ml of methylene chloride were passed into a mixture of 27.2 g of palmitic acid with vigorous reflux until saturation of boron trifluoride. After standing overnight, the mixture was boiled under reflux for a further hour and then decomposed in a solution of 25 g of Na acetate in 220 ml of water with stirring. After 45 minutes the methylene chloride solution was separated and evaporated. The residue was stirred with methanol and suction filtered.

0034Recrystallized from n-chlorobutane, 21 g were obtained at F 90-93 ° C

Step 2: 4-Hydroxy-2-methyl-5-hexadecanoylphenyl allyl ether

00356.9 g of allyl bromide were added to a mixture of 17.5 g of the keto compound from stage 1, 10.2 g of potassium carbonate and 200 ml of methyl ethyl ketone with stirring and refluxing in the course of 60 minutes under a nitrogen atmosphere. After a total of 9 hours of refluxing, the reaction mixture was mixed with 100 ml of water. The methyl ethyl ketone layer was separated, shaken twice with 20% sodium chloride solution and dried with sodium sulfate. The residue which remained after the solvent had been evaporated off was stained with methanol and the resulting precipitate was recrystallized from methanol after suction.

0036Yield: 12.5 g / F 44-47 ° C

Step 3: 2-methyl-6-allyl-5-hexadecanoyl hydroquinone

003712th g of allyl ether from stage 2 were subjected to the Claisen rearrangement as described in Preparation Example 1, stage 3. After cleaning with gasoline (50 - 75 ° C) 8.5 g yield with F 65 - 67 ° C were obtained.

Step 4: 2-methyl-6-propyl-5-hexadecanoyl hydroquinone

00388th g of allyl hydroquinone from stage 3 were hydrogenated as described in preparation example 1, stage 4, and the resulting product was also recrystallized from gasoline.

0039Yield: 6.5 g / F 66-68 ° C. Mare 5: 2-methyl-6-propyl-5-α-hydroxy-hexadecylhydrochincn

00406.5 g of the keto compound from stage 4 were dissolved in 90 ml of Methanel and hydrogenated with a solution of 0.75 g of sodium borohydride in 3 ml of water as described in Preparation Example 1, stage 5, and the crude carbinol was recrystallized from methanol.

0041Yield: 5 g / F 121-124⁰C.

Step 6: dye sulfinic acid 4- {3- [8- (4-nitro-2-methylsulfonylphenylzo) -5-hydroxy-1-naphthyl] sulfamoylbenzene} sulfionamido benzene sulfinic acid

0042In a solution of 4.9 g of potassium carbonate, 3.75 g of aminobenzenesulfinic acid, 44 ml of water and 62.5 ml of acetone, 10 g of 3- [8- (4-nitro-2-methylsulfonyl-phenylazo) -5- hydroxy-1-naphthyl] sulfamoyl benzenesulfochloride entered. After 30 minutes, the mixture was filtered and 250 ml of water and 31 ml of concentrated hydrochloric acid were added to the solution in succession. The resulting precipitate was filtered off and washed with water. Dried in a drying cabinet.

0043Yield: 10.6 g Stage 7: Compound No. 11

0044Under a nitrogen atmosphere, a filtered 85 ° C. solution of 8.9 g of dye sulfinic acid 1 g of sodium acetate sicc was added to a solution of 4.1 g of carbinol compound from stage 5 in 250 ml of glacial acetic acid at 60-65 ° C. with stirring. placed in 200 ml of glacial acetic acid and 120 ml of water and stirred at 60-65 ° C. for 1 hour. After cooling, the resulting precipitate was filtered off and recrystallized from ethyl acetate / methanol with the addition of activated carbon.

Yield: 5.5 g

0045The main aspect of the present invention relates to the case where the oxidizable compound is a coloring compound and the photographically active group is a diffusing dye. For this reason, the following mainly refers to coloring compounds, but this should not be understood as a limitation. In fact, the oxidizable compounds can be used for a wide variety of other purposes, with other photographically active groups being possible. The coloring compounds according to the invention are incorporated into the casting solutions for the layers of the photographic material by one of the customary methods. The amount of coloring compound used per liter of casting solution varies within relatively wide limits, the most favorable concentration being determined on the basis of simple experiments. For example, 5-80 g, preferably 20-40 g, of coloring compound are used per liter of casting solution.

0046The association between diffusion-resistant coloring compound and silver halide required to achieve the desired effect can be produced, for example, by introducing the diffusion-resistant compounds from the aqueous solution into the casting solutions using existing acidic water-solubilizing groups. However, the non-diffusing coloring compounds can also be introduced into the layers by one of the known emulsification processes. Such methods are described, for example, in British Patents 791,219 and 1,099,414 to 1,099,417. Furthermore, it is possible to prepare aqueous dispersions or coloring compounds and add them to the respective casting solutions. For this purpose, aqueous slurries of the coloring compounds are finely ground, for example by intensive stirring with the addition of sharp-edged sand or by using Ulese. In a further embodiment it may be desirable, for example, to store the coloring compounds together with silver halide and, if appropriate, developer substances in the form of so-called microcapsules, two or more differently sensitized light-sensitive silver halide emulsions and the corresponding diffusion-resistant compounds in a single layer in the manner of the so-called Mixed grain emulsions are combined, as described, for example, in U.S. Patent 2,698,794. The non-diffusing coloring compounds can be accommodated in a light-sensitive layer itself or in a neighboring layer. For example, the red-sensitive layer is associated with a compound that cleaves off a cyan dye, the green-sensitive layer is associated with a compound that cleaves off a purple dye, and the blue-sensitive layer is associated with a compound that cleaves off a yellow dye.

0047"Assignment" and "assigned" is understood to mean that the mutual arrangement of silver halide emulsion and coloring compound is of such a kind that an interaction between them is possible which permits a pictorial correspondence between the silver image formed and the pictorial distribution of oxidized non-diffusing coloring compound.

0048In this case, the assigned coloring compound is expediently incorporated into the silver halide emulsion itself or into a layer adjacent to the silver halide emulsion layer, this adjacent layer preferably being located behind the silver halide emulsion layer (viewed in the direction of the light incident during exposure). The color-imparting compounds according to the invention are oxidized imagewise during the development of the silver image of developer oxidation products; the non-oxidized portions of the coloring compounds are then subject to a cleavage reaction under the influence of the developer or activator alkali, in which the dye residues are released in a diffusing form. The usual photographic silver halide developing agents are suitable for development insofar as they are able to oxidize the color-imparting compounds according to the invention in oxidized form. Examples of suitable developers are as follows:<ul id="ul0003" list-style="none"><li>Hydroquinone</li><li>N-methylaminophenol</li><li>1-phenyl-3-pyrazolidone</li><li>1-phenyl-4,4-dimethyl-3-pyrazolidone</li><li>1-phenyl-4-methyl-4-hydroxymethyl-3-pyrazolidone 1-phenyl-4,4-bishydroxymethyl-3-pyrazolidone</li><li>Aminophenols</li><li>N, N-diethyl-p-phenylenediamine</li><li>N-ethyl-N-hydroxyethyl-p-phenylenediamine and 3-methyl-N, N-diethyl-p-phenylenediamine</li><li>N, N, N ', N'-tetraalkyl-p-phenylenediamines such as tetramethyl-p-phenylenediamine</li><li>Triethylsulfobutyl-p-phenylenediamine and 1,4-bis-pyrrolidinobenzene reductones</li></ul>

0049It should be pointed out in particular that the selection of developer substances in the process according to the invention is not limited to color developers, but that conventional black-and-white developers are preferably also used, which is to be regarded as an advantage because of the lower tendency to discoloration of the latter.

0050The developers can already be contained in the layers of the color photographic material, where they are activated by the alkaline activator liquid, or in the alkaline processing liquid or paste. Since the coloring compounds according to the invention themselves have developer properties, the use of auxiliary developer compounds can be dispensed with under certain conditions. In this case, the coloring compound is immediately oxidized by developable silver halide.

0051Since the image-wise distribution of the diffusing dye released during development coincides with the image-wise distribution of the undeveloped silver halide, it is not necessary to use direct-positive silver halide emulsions or the use of a suitable reversal process to produce positive colored transfer images, but conventional negative emulsions can be used .

0052The emulsions can be chemically sensitized, for example by adding sulfur-containing compounds during chemical ripening, for example allyl isothiocyanate, allyl thiourea, sodium thiosulfate and the like. Reducing agents, for example the tin compounds described in Belgian patents 493 464 and 568 687, furthermore polyamines such as diethylenetriamine or aminomethanesulfinic acid derivatives, for example, can also be used as chemiseve sensitizers according to Belgian patent 547 323 can be used.

0053Precious metals or noble metal compounds such as gold, platinum, palladium, iridium, ruthenium or rhodium are also suitable as chemical sensitizers. This method of chemical sensitization is described in the article by R. KOSLOWSKY, Z.Wiss.Phot. 45, 65-72 (1951).

0054It is also possible to sensitize the emulsions with polyalkylene oxide derivatives, for example with polyethylene oxide with a molecular weight between 1000 and 20,000, furthermore with condensation products of alkylene oxides and aliphatic alcohols, glycols, cyclic dehydration products of hexitols, with alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic Amines, aliphatic diamines and amides. The condensation products have a molecular weight of at least 700, preferably more than 1000. To achieve special effects, these sensitizers can of course be used in combination, as described in BE-PS 537 278 and in GB-PS 727 982.

0055The emulsions can also be spectrally sensitized, for example by the customary mono- or polymethine dyes such as acidic or basic cyanines, hemicyanines, streptocyanine merocyanines, oxonols, hemioxonols, styryl dyes or other, also trinuclear or polynuclear methine dyes, for example rhodacyanines or neocyanines. Such sensitizers are described, for example, in the FM work HAMER "The Cyanine Dyes and Related Compounds" (1964) Interscience Publishers John Wiley and Sons, New Yorko

0056The emulsions can contain the usual stabilizers, such as, for example, homopolar or salt-like compounds of mercury with aromatic or heterocyclic rings such as mercaptotriazoles, simple mercury salts, sulfonium mercury double salts and other mercury compounds. Also suitable as stabilizers are azaindenes, preferably tetra- or penta-azaindenes, in particular those which are substituted by hydroxyl or amino groups. Such compounds are described in the article by BIRR, Z.Wiss.Phot. 47, 2-27 (1952). Other suitable stabilizers include heterocyclic mercapto compounds, for example phenyl mercaptotetrazole, quaternary benzothiazole derivatives, benzotriazole and the like.

0057Gelatin is preferably used as a binder for the photographic layers. However, this can be replaced in whole or in part by other natural or synthetic binders. Examples of suitable natural binders are alginic acid and its derivatives such as salts, esters or amides, cellulose derivatives such as carboxymethyl cellulose, alkyl cellulose such as hydroxyethyl cellulose, starch or their derivatives such as ethers or esters, or caragenates. Synthetic binders include polyvinyl alcohol, partially saponified polyvinyl acetate, polyvinyl pyrrolidone and the like.

0058The layers can be cured in the customary manner, for example using formaldehyde or halogen-substituted aldehydes which contain a carboxyl group, such as mucobromic acid, diketones, methanesulfonic acid esters, dialdehydes. To carry out the dye diffusion transfer process according to the present invention, a light-emitting element is used which contains one or more silver halide emulsion layers and the associated non-diffusing coloring compounds and an image-receiving element in which the desired color image is generated by the imagewise transferred diffusing dyes. This requires that there be firm contact between the photosensitive member and the image-receiving member for at least a finite period within the development time, so that the photosensitive member as a result of the development. generated image-like distribution of diffusing dyes can be transferred to the image receiving element. The contact may be made after development has started or it may have been established before development begins. The latter is the case, for example, if a material is used to carry out the dye diffusion transfer process in which the light-sensitive element and the image-receiving element form an integral unit, also referred to below as mono-sheet material, which continues to exist even after the development process has ended, ie a separation the photosensitive element from the image receiving element is not provided even after color transfer has taken place. Such an embodiment is described for example in DE-OS 2 019 430.

0059A mono-plate material suitable for carrying out the dye diffusion transfer process according to the present invention has, for example, the following layer elements:<ul id="ul0004" list-style="none"><li>1) a transparent substrate</li><li>2) an image receiving layer</li><li>3) an opaque layer</li><li>4) a light-sensitive element with at least one light-sensitive silver halide emulsion layer and at least one non-diffusing coloring compound associated therewith</li><li>5) a retardation layer</li><li>6) an acidic polymer layer</li><li>7) a transparent substrate</li></ul>

0060The mono-sheet material can be composed in such a way that two different parts are produced separately from one another, namely the light-sensitive part (layer elements 1 - 4) and the cover sheet (layer elements 5 - 7), which are then placed on top of one another on the layer side and connected to one another, optionally under Use of spacer strips, so that a space for receiving a precisely measured amount of processing liquid is formed between the two parts. The layer elements 5 and 6, which together form the neutralization system, can also be arranged - albeit in the opposite order - between the layer support and the image-receiving layer of the light-sensitive part. Means can be provided to introduce a processing liquid between the light-sensitive part and the cover sheet, for example in the form of a laterally arranged splitable container which, when subjected to mechanical forces, pours its contents between two adjacent layers of the monosheet material.

0061An essential part of the photographic material according to the present invention is the photosensitive element which, in the case of a single dye transfer process, contains a photosensitive silver halide emulsion layer and associated with it a non-diffusing coloring compound. The non-diffusing compound can be in a silver halide emulsion schioma. adjacent layer or in the silver halide emulsion layer itself, in the latter case the color of the image dye is preferably selected so that the predominant absorption range of the coloring compound does not match the predominant sensitivity range of the silver halide emulsion layer. In order to produce multicolored transfer images in true-to-life colors, however, the light-sensitive element contains three such assignments of coloring compound and light-sensitive silver halide emulsion layer, the absorption range of the coloring compound generally matching the range of spectral sensitivity of the assigned silver halide emulsion layer. A prerequisite for the highest possible sensitivity is, however, that the color-providing combination is arranged in a separate binder layer (seen in the direction of the light incident during the exposure) behind the silver halide emulsion layer. The developer oxidation products resulting from the development of a silver halide emulsion may of course only have an effect on the assigned coloring compound. Separating layers are therefore generally present in the photosensitive element, which effectively prevent the diffusion of the developer oxidation products into other unassigned layers.

0062These separating layers can contain, for example, suitable substances which react with the developer oxidation products, for example non-diffusing hydroquinone derivatives or, if the developer is a color developer substance, non-diffusing color couplers. In a preferred embodiment, the photosensitive element therefore has the following structure (from top to bottom):<ul id="ul0005" list-style="none"><li>Blue-sensitive silver halide emulsion layer. Layer with non-diffusing, separating layer that releases a diffusing yellow dye</li><li>Green-sensitized silver halide emulsion layer with non-diffusing, separating layer that releases a diffusing purple dye</li><li>red-sensitized silver halide emulsion layer layer with non-diffusing, a diffusing blue-green dye releasing compound</li></ul>

0063Of course, the silver halide emulsion layers can also be arranged in a different order, but the assigned layers must also be interchanged with the coloring systems so that the assignment is retained.

0064The opaque layer arranged under the photosensitive element is permeable to aqueous alkaline treatment solutions and thus to the diffusing dyes. It essentially has two functions: firstly, it serves to cover the image silver remaining in the originally light-sensitive element after development, as well as the color-providing compounds remaining as color negative, so that when viewed through the transparent layer support of the light-sensitive part, only the positive color transfer image is visible ; second, it closes the light-sensitive element in a light-tight manner on the side of the image-receiving layer (downward). The latter is particularly important if, after exposure, the mono-sheet material is still brought into contact with the alkaline processing compound in the camera, then is to be pulled out of the camera and developed outside the camera.

0065Layers with sufficient opacity but sufficient permeability for diffusing dyes can be produced, for example, with suspensions of inorganic or organic dark, preferably black pigments, for example with suspensions of carbon black, in suitable binders, for example in gelatin solutions. Generally 0.5 - 2 is sufficient_/u Strong layers containing 10 - 90% by weight (based on the total dry weight) of carbon black in gelatin in order to ensure that the light is excluded to a sufficient extent during development. The particle size of the pigments used is relatively uncritical as long as it is 0.5_/u does not significantly exceed.

0066In addition to the black pigment layer, the opaque layer preferably also comprises a white pigment layer arranged underneath. Its task is to cover up the black layer and to create a white background for the picture. All white pigments are suitable for this, provided that their opacity is sufficiently high for layers that are not too large. Examples include barium sulfate, oxides of zinc, titanium, silicon, aluminum and zircon, and also barium stearate or kaolin. Titanium dioxide is preferred as the white pigment. The same information applies to the binder, the concentration and the particle size as for the black pigments. The thickness of the white pigment layer can be varied depending on the desired whiteness of the substrate. Thicknesses between 5 and 20μ are preferably used.

0067Instead of the opaque layer, means for producing such an opaque layer can also be arranged in the monosheet material according to the present invention between the photosensitive element and the image-receiving layer, for example in the form of a laterally arranged container with a processing liquid containing an opacifying agent (pigment) which, when subjected to mechanical forces, pours its contents between the layers mentioned, so that such a pigment layer forms there.

0068The image-receiving layer essentially consists of a binder which contains dye mordants for the determination of the diffusing dyes.

0069Long-chain quaternary ammonium or phosphonium compounds or ternary sulfonium compounds, for example those as described in US Pat. Nos. 3,271,147 and 3,271,148, are preferably used as mordants for acid dyes Dyes form poorly soluble compounds can be used. The dye mordants are dispersed in the receiving layer in one of the usual hydrophilic binders, for example in gelatin, polyvinylpyrrolidone, wholly or partially hydrolyzed cellulose esters and the like. Of course, some binders can also act as mordants, for example copolymers or polymer mixtures of vinyl alcohol and N-vinylpyrrolidone, as described, for example, in DE-AS 1 130 284, and also those which are polymers of nitrogen-containing quaternary bases, for example Polymers of N-methyl-2-vinylpyridine, as described, for example, in US Pat. No. 2,484,430.

0070At this point, reference may also be made to the crosslinking products of hydrophilic binders with quaternary polyurethanes bearing glycidyl groups described in DE-OS 2 631 521. Other usable mordants for the detergents are, for example, guanylhydrazone derivatives of acylstyrene polymers, such as, for example, described in DE-OS 2 009 498. In general, however, other binders, for example gelatin, will be added to the latter mordants.

0071The transparent support materials used in photographic practice, for example films made of cellulose esters, polyethylene terephthalate, polycarbonate or other film-forming polymers, can be used as the transparent support for the monosheet material according to the invention. The alkaline processing composition sets a relatively high pH waiting (about 11 to 14) in the light-sensitive material, which triggers the development and the imagewise dye diffusion. It has been shown that at this high pH the dyes and thus the images obtained are not particularly stable. It is therefore necessary that the material is made almost neutral or slightly acidic after development. This can be achieved in a known manner in that the material additionally contains an acidic polymer layer which is only gradually accessible to the alkaline processing composition in the course of development. An acidic polymer layer is understood to mean a binder layer which contains polymeric compounds with acid groups, preferably sulfo or carboxyl groups. These acidic groups react with the cations of the processing mass with salt formation and lower the pH of the mass. Of course, the polymeric compounds and thus the acidic groups are embedded in the layer mentioned in a diffusion-resistant manner. The acidic polymers are derivatives of cellulose or derivatives of polyvinyl compounds; however, other polymeric compounds can also be used. Examples of useful acidic polymers are: cellulose derivatives with a free carboxyl group, for example Cellulosedicarbonsäurehalbester with a free carboxyl group such as cellulose acetate hydrogen phthalate, Celluloseacetathydrogenglutarat, Ethylcelluloseacetathydrogensuccinat, Celluloseacetathydrogensuccinathydrogenphthalat, ethers and esters of cellulose, which are modified with other dicarboxylic acid anhydrides or sulfonic acid anhydrides, such as o-sulfobenzoic anhydride, carboxymethylcellulose, also polystyrene, polyvinyl, Polyvinylacetathydrogenphthalat, Polyacrylic acid, acetals of polyvinyl alcohol with aldehydes which are substituted by carboxy or sulfo groups, such as o-, m- or p-benzaldehyde sulfonic acid or carboxylic acid, partially esterified ethylene-maleic anhydride copolymers, partially esterified methyl vinyl ether-maleic anhydride copolymers and the like.

0072Suitable acidic polymers are described for example in DE-OS 2 652 464.

0073The acidic polymer layer must contain enough acid groups to lower the pH of the processing mass from the beginning 11 to 14 to such an extent that the material is finally almost neutral or slightly acidic (pH 5-8).

0074The time delay of the pE value reduction is achieved in a known manner in that the acidic polymer layer is coated with a so-called delay layer. This retardation layer represents an alkali-impermeable layer, which preferably consists of a polymer which is inert towards alkali, for example of polyvinyl alcohol or a partially acetalized polyvinyl alcohol. By a suitable choice of the thickness and the composition of this delay layer, the time delay of the pH reduction can be adjusted in the desired manner. A brake layer with polymers of a novel permeability behavior is described, for example, in DE-OS 2 455 762.

0075Neutralization systems, which are combinations of an acidic polymer layer and a retardation layer, are described, for example, in DE-FS 1 285 310. Such layer combinations can be present in the material according to the invention, for example in the light-sensitive part between the transparent layer support and the image-receiving layer.

0076Another possibility is to arrange the neutralization system from the acidic polymer layer and a retardation layer on the cover sheet. Of course, these two layers must be arranged in such a sequence that the alkali of the processing composition must first penetrate the retardation layer in order to get into the acidic polymer layer.

0077The dye diffusion transfer method according to the invention can advantageously be carried out in or by means of a suitable self-developing camera. This can be provided, for example, with devices which, after exposure of the photosensitive element, make it possible to distribute a working solution between the latter and the cover sheet and to cover the photosensitive material in an opaque manner. Such a camera is preferably provided with two nip rollers mounted against one another, between which the mono-sheet material is pulled out, the laterally arranged containers being split up and releasing their contents between the layers of the mono-sheet material. Since the light-sensitive element is protected from unwanted exposure by opaque layers on both sides after passing through the nip rollers, the exposed material can be pulled out of the camera immediately after development has been started.

0078To process the imagewise exposed monosheet material, the photosensitive element is brought into contact with the aqueous alkaline working solution. In this case, the imagewise exposed silver halide emulsion layers are developed in the presence of the developer compound, an imagewise distribution of oxidation products of the developer compound being generated in accordance with the silver image thereby formed, which oxidizes the associated coloring compound, followed by the imagewise distribution of unoxidized coloring compound under the action the activator or Developer alkali the diffusing dye is split off.

0079The aqueous alkaline working solution can contain viscosity-increasing additives, for example hydroxyethyl cellulose. Development accelerators, stabilizers, silver salt solvents, fogging agents, antioxidants and other additives can also be contained in the working solution in a known manner.

0080Since the compounds according to the invention are essentially only subjected to hydrolytic cleavage in the reduced state with the release of the photographically active group, but are stable after oxidation, it is obvious to also incorporate them into the layers in the oxidized form, but care must be taken must be converted imagewise into the hydrolyzable reduced form during development. This can be accomplished by the simultaneous use of so-called electron donor compounds (ED compounds), which are reducing substances which are converted into the oxidized form by reaction with developer oxidation products or with the developable silver halide and thus the reaction with the oxidized Form of the compounds of the invention are withdrawn. The ED compound remains in its active form only at those points where there is no development of silver halide, which can react with the oxidized form of the coloring compound to form the hydrolyzable reduced form, from which, under the conditions of photographic development, the diffusing dyes are released imagewise. With regard to such procedures, reference is made, for example, to DE-OS 2 809 716, which also describes a number of suitable ED compounds.

0081The invention has been explained above with reference to examples in which the photographically active group is a diffusing dye or diffusing dye precursor. However, other embodiments are also appreciated in which the photographically active group is, for example, an antifoggant, a development inhibitor, a hardening agent, a developing agent or an accelerating agent. In all of these cases the photographically active group is released imagewise, ie in accordance with the imagewise distribution of undeveloped silver halide when using negative emulsions. This results in a wide range of options for image generation.

Embodiment 1

0082A pickling layer, a light-reflecting layer and a light-sensitive silver halide emulsion layer were applied to a transparent cellulose triacetate support in the following order:<ul id="ul0006" list-style="none"><li>Stain layer:</li><li>3.75 g of a copolymer of one part of styrene and one part of maleimide of N, N-dimethyl-N-hexadecyl-NW-aminopropyl-ammonium bromide were dissolved in 15 ml of ethanol and this solution was stirred into 75 ml of 5% gelatin solution and homogenized . After adding 2.6 ml of 5% saponin solution and 1 ml of 2% aqueous mucochloric acid solution, a customary pouring viscosity (approx. 11 mPa.s) and the solution was applied to the support at 40 ° C. by immersion (casting speed 5 m / min).</li></ul>

0083Light reflecting layer:<ul id="ul0007" list-style="none"><li>A slurry of 42 g Ti0₂ in 20 ml of water with the addition of 5 ml of 5% aqueous solution of sodium dodecylbenzenesulfonate and 5 ml of 5% aqueous saponin solution in 150 ml of 8% aqueous gelatin solution. After adding 1 ml of 2% mucochloric acid solution, the dispersion was adjusted to a viscosity of 13 mPa.s at 40 ° C. and applied to the dried pickling layer by immersion (casting speed 5 m / min).</li></ul>

0084Silver halide layer:<ul id="ul0008" list-style="none"><li>1 mol each of the oxidizable compounds listed in the following table were dissolved in 3 ml of caprylic acid diethylamide and 3 ml of ethyl acetate and dispersed in 25 ml of 5% gelatin solution with the addition of 5 ml of 5% aqueous solution of sodium dodecylbenzenesulfonate. After further addition of 50 ml of 5% gelatin and 1 ml of 2% mucochloric acid solution, each of the dispersions was mixed with 18 g of a ready-to-pour silver halide emulsion. This silver halide emulsion was made with 74 g of AgNO₃ per kg of emulsion; it had an Ag: gelatin ratio of 1: 1.1 and the halide was mainly bromide with 0.67 mol% iodide. The mixtures were applied to the dried light-reflecting layer at a speed of 5 m / min at 40 ° C. using the immersion method.</li></ul>

0085After drying, the various samples were exposed through a grayscale filter on the emulsion side, developed in the developer described below for 4 minutes at 18 ° C., washed and dried.

0086Developer:<ul id="ul0009" list-style="none"><li>1.5 g of sodium ethylenediaminetetraacetic acid salt</li><li>11.5 g borax</li><li>1.0 g sodium hexametaphosphate</li><li>2.0 g of 1-phenylpyrazolidone</li><li>3.0 g KBr</li><li>make up to 1000 ml with water and</li><li>adjust to pH 12.5 with 1N NaOH</li></ul>

0087Fully developed positive color wedges were obtained from each of the samples, which were visible through the transparent layer support. The color densities (D_min and Dmax) were measured behind color filters using a reflection densitometer and are summarized in the following table:<tables id="tabl0001" num="0001"><img file="EP0012908A2_D0028.tif" /></tables> The table contains a comparison with the corresponding dyes of German patent application P 28 23 159.6, which are in the o-position to the carbinol carbon atom (R.⁵) contain a hydrogen atom instead of a non-deprotonatable substituent. The compounds A, B, C and D have the following formulas:<chemistry id="chem0028" num="0028"><img file="EP0012908A2_D0029.tif" /></chemistry><chemistry id="chem0029" num="0029"><img file="EP0012908A2_D0030.tif" /></chemistry><chemistry id="chem0030" num="0030"><img file="EP0012908A2_D0031.tif" /></chemistry><chemistry id="chem0031" num="0031"><img file="EP0012908A2_D0032.tif" /></chemistry>